1. Field of the Invention
The present invention relates to a color picture tube apparatus used in a television, a computer display, or the like.
2. Description of the Related Art
In order to reduce a deflection power and suppress the heat generated by a deflection yoke, JP61(1986)-56757U discloses a so-called slot core in which a plurality of convex portions protruding toward a tube axis of a picture tube are provided on an inner surface of a ferrite core constituting a deflection yoke. FIG. 7 shows a cross-sectional view of the deflection yoke with the slot core, taken along a surface vertical to the tube axis at a position close to an electron gun. Reference numeral 9 denotes a ferrite core, and 10 denotes a plurality of convex portions provided on an inner surface of the ferrite core 9. Windings are inserted in grooves between the convex portions 10 adjacent to each other in a circumferential direction, whereby a vertical deflection coil 7 and a horizontal deflection coil 6 are wound therein. Reference numeral 8 denotes an insulating spacer for insulating the vertical deflection coil 7 from the horizontal deflection coil 6. Each convex portion 10 extends over the entire region in a tube axis direction from an end on an electron gun side of the ferrite core 9 to an end on a screen side thereof, along a surface including the tube axis. By providing such convex portions 10, compared with the case where the convex portions 10 are not provided, the ferrite core 9 can be brought close to the picture tube. Therefore, the deflection efficiency can be enhanced, which is advantageous for reducing a deflection power. Furthermore, since a magnetic flux is unlikely to cross the coils 6, 7, an eddy current loss-is reduced, and the heat generated by the deflection yoke also can be decreased.
In the slot core of JP61(1986)-56757U, windings of the horizontal deflection coil 6 and the vertical deflection coil 7 are inserted to be wound in the grooves between the plurality of convex portions 10 extending between both ends in the tube axis direction of the ferrite core 9. Therefore, it is necessary to arrange the winding of the horizontal deflection coil 6 and the winding of the vertical deflection coil 7 along the common grooves so as not to allow them to extend off the grooves over the entire length in the tube axis direction of the ferrite core 9. Thus, there is a limit to the degree of freedom in a winding arrangement.
In order to solve the above-mentioned problem, JP7(1995)-35289Y proposes a ferrite core 9 in which convex portions 10 are provided only in a partial region on an electron gun side in a tube axis direction. FIG. 8 shows a front view of the ferrite core 9 seen from a screen side. In the ferrite core 9 shown in FIG. 8, the convex portions 10 are not formed on an inner surface on the screen side. Thus, by freely setting the winding arrangement of a horizontal deflection coil and a vertical deflection coil in a region where the convex portions 10 are not formed, a deflection magnetic field distribution can be adjusted appropriately, so that a color shift and raster distortion can be reduced.
However, the slot core shown in FIG. 8 cannot sufficiently satisfy the recent request for further reducing a deflection power.